DEAR MISS MANNERS: I am an acquaintance of identical twins who look so similar that it is hard to distinguish who is who. We all participate in the same recreational activity, so I am often in a situation of wanting to greet one of them, but not knowing which twin I am greeting. Should I just say “Hello” or “Good morning” with no name attached? Or take a guess at which twin it is and hope I don’t get it wrong? The other day, I greeted one of them by name (I took a guess) and then immediately apologized for possibly having gotten her name wrong. She responded with a smile and a “don’t worry abo…